Blood platelets collected for transfusion must be stored at room temperature to maximize their survival in a functional state. Bacteria may be introduced into stored platelets during the collection process or as a result of unnoticed bacteremia in the donor(s); room temperature storage is substantially more conducive to the growth of more bacterial species than are the lower storage temperatures used for other blood components. The risk of contamination limits platelet shelf life to 5 days, although it has been established that contamination-free units remain effective for at least 7 days. Approved methods of bacterial detection require incubation of the test sample, typically for 24 hours, shortening effective shelf life. Although direct detection of bacteria in stored platelets has been demonstrated using fluorescence-based imaging cytometry, the required apparatus has, to the present, been too expensive to be cost-effective. However, recent advances in electro-optic technology, notably high-intensity light-emitting diodes (LEDs) and efficient charge-coupled device cameras (CCDs), now make it feasible to produce simple automated fluorescence image cytometers, salable for well under $10,000, that could be clinically useful. This project will demonstrate the capacity of such apparatus to detect and count common bacterial contaminants seeded into platelet units at concentrations as low as 100 colony forming units (CFU)/mL, using nucleic dyes and other fluorescent reagents to stain and identify organisms concentrated onto membrane filters following detergent lysis of platelets and other formed elements of blood, with a detection time on the order of one hour.